This invention relates to an embossed carrier tape suitable for use for feeding of electronic components to an electronic component mounting apparatus, transportation of the components, storage thereof or the like while receiving them in receiving recesses formed on the tape in a manner to be spaced from each other at predetermined intervals in a longitudinal direction of the embossed carrier tape, and more particularly to an embossed carrier tape which permits an image of each of electronic components received in the receiving recesses of the tape to be picked up by a camera, resulting in a signal of the picked-up image generated from the camera being processed, leading to inspection of bending or deformation of leads of each of the electronic components or the like.
A package for an electronic component such as a semiconductor package or the like has conventionally used a packaging material such as a paper tape, a magazine, a tray, an embossed carrier tape (hereinafter also referred to as "carrier tape") or the like. In recent years, the carrier tape has been predominantly used for this purpose because it permits mounting of the electronic components to be accomplished with increased efficiency and facilitates handling of the electronic components. In particular, a progress in reducing a size of an IC package for a semiconductor device and arrangement thereof at fine pitches leads to predominant use of the carrier tape for the package.
The carrier tape is formed by subjecting a thermoplastic resin material such as polystyrene, polyvinyl chloride, amorphous polyester, polycarbonate, polypropylene, polyethylene terephthalate or the like to any suitable forming treatment such as press forming, vacuum forming, pressure forming, vacuum-pressure forming, pressure plugassist forming or the like to provide receiving recesses in which electronic components are to be received. During charging of the electronic components in the receiving recesses of the carrier tape thus formed, the electronic components are subjected to an inspection of a function or performance of the electronic components such as electric properties thereof and the like and a visual inspection for inspecting an appearance of the electronic components such as any defect or deficiency of the electronic components, any marking on a surface of the components or the like. Thereafter, the electronic components are received in the receiving recesses of the carrier tape and then a top tape is adhered to the carrier tape to close an opening of each of the receiving recesses. Then, a final inspection is carried out on the carrier tape prior to shipping, to thereby visually inspect a direction or posture of insertion of the electronic components into the receiving recesses of the carrier tape, inclusion of any improper electronic components into the carrier tape, a production lot of the electronic components, any marking on the components, lack of the components required, deformation of leads of the components and the like.
Unfortunately, each of the visual inspections described above necessarily or inevitably depends on inspector's individual judgment. Such individual judgment tends to be varied in criteria and readily cause an error, and requires a lot of inspection steps. Also, it substantially fails to accurately or satisfactorily inspect a small-sized semiconductor package in which leads are arranged at reduced pitches, because it is visually carried out. In view of the foregoing, it has been recently attempted to automatically carry out each of the visual inspection prior to adhesion of the top tape to the carrier tape and the final visual inspection by means of an inspection unit using a camera or the like and, as a result, such an automatic inspection has been partially put into practice.
More particularly, such an inspection unit as described above is generally constructed in such a manner that light emitted from a light emitting diode (LED), an optical fiber or the like is downwardly irradiated on the electronic components in the receiving recesses of the carrier tape and then an image of the electronic components is picked up by means of a CCD camera or the like, resulting in the CCD camera generating a signal of the thus picked-up image or an imaging signal. Then, the imaging signal thus generated is used for image processing such as binary processing, gray scale pattern matching or the like, so that any marking on an upper surface of the electronic components, deformation of the leads and the like may be inspected.
In the conventional carrier tape described above, the receiving recesses are formed into a size somewhat greater than that of the electronic components, to thereby facilitate insertion of the electronic components into the receiving recesses and removal of the former from the latter. Also, the receiving recesses of the carrier tape are each formed on a side surface thereof with an inclination or draft for facilitating removal of the receiving recesses from a forming die after forming of the recesses. Further, the leads of each of the electronic components are each formed at distal ends thereof with a flat portion, of which an upper surface highly reflects light. Moreover, lighting obtained by the inspection unit during the inspection tends to be reduced on a periphery of a bottom surface side of the electronic components as compared with an upper surface thereof. Thus, inspection by the inspection unit, prior to adhesion of the top tape to the carrier tape, in which insertion of the electronic components into the receiving recesses of the carrier tape are carried out results in a failure; because when the electronic components are received in the receiving recesses in a manner to be deviated from a correct position or in a wrong posture due to undesirable movement of the electronic components therein, resulting in the leads of the electronic components being abutted at distal ends thereof against the side surface of the receiving recesses, a reflected image of the leads occurs from the side surface of the receiving recesses in a manner to be contiguous to a directly-viewed image thereof. This causes image processing of the imaging signal of the camera to fail in accurate recognition or identification of the leads, leading to a failure in inspection of the leads of the electronic components.
In order to solve the problem, a carrier tape which is constructed so as to have a certain roughness of an inner surface of receiving recesses has been proposed as disclosed in Japanese Utility Model Registration No. 3,001,281. Another carrier tape has also been proposed which is constructed so as to provide a coating layer on an inner surface of receiving recesses to reduce glossiness of the inner surface to a level of 50 or less, as disclosed in Japanese Patent Application Laid-Open Publication No. 143094/1996. Unfortunately, such proposed carrier tapes each fail to fully solve the problem.